FITBIT IONIC

Starting a workout on the Ionic is as simple as pressing the "go" arrow at the bottom-right corner of the display or hitting the bottom-right button on the side. All of the Ionic's workouts are "quick start" in this sense. (Apple has also updated its Workout app in watchOS 4 to have quick-start options. Before the watchOS 4 update, only your most-used workouts would start immediately upon hitting the icon in the Workout app. All others would ask you to define a workout goal based on distance, time, or calories burned.) But you can't define a goal for an individual workout with the Ionic.

During a workout, the Ionic's display shows three stats at a time. You can customize these from each exercise's settings directly on the watch, choosing data that appears on the top, bottom, and middle of the display. By default, top and bottom stats are already chosen, but you can swipe on the middle section of the display to scroll through all available data including time, steps, calories, heart rate, distance, and pace information. I liked having that flexibility with the middle section, but I always made sure that the data most important to me was set for the top and bottom sections. You can customize visible in-workout stats on the Apple Watch as well (it can show four at a time on the display), but you can't do so on the watch; you have to edit settings in the Watch app on iOS.

Fitbit includes a Weight exercise shortcut on the Ionic; however, it doesn't have a rep counting or exercise recognition feature. Android Wear 2.0 added support for rep counting and some exercise recognition, allowing you to lift weights, input the amount of weight lifted, and complete exercises like crunches or bicycles with ease. New Garmin devices like the $140 Vivosmart 3 count reps as well, so it seems like Fitbit missed an opportunity on that front.

Heart rate monitorInside the Ionic is Fitbit's PurePulse heart rate monitoring technology that also appears in its other fitness trackers, including the Alta HR. While the Ionic's heart rate monitor floundered the first few times I used it (it was 20 BPMs off a couple of times), I didn't experience many problems after that. Fitbit recommends wearing the Ionic three-fingers-width away from your wrist bone—and tight enough so it can't wobble. The Ionic's heart rate monitor was solid most of the time when compared to the Polar H10 heart rate chest strap and to the heart rate monitor on the Apple Watch Series 2, reading my heart rate within 2 BPM of those other devices.

GPSThe GPS inside the Ionic worked as expected. It took about one minute for the GPS to grab my location before an outdoor run. That's not fast, but you don't have to wait for the GPS to find your location before heading out, and once I started, the device did map my route accurately.

The Ionic is a major improvement over the GPS in the Fitbit Surge, which was released about three years ago. The Blaze only had "connected GPS," meaning it knew your location only by using your smartphone's GPS (which meant carrying your phone when working out). Considering the Fitbit Surge will likely be replaced by the Ionic, it's good to see Fitbit make onboard GPS a solid feature on its high-end tracker.

Sleep trackingThe Ionic outshines the Apple Watch in sleep tracking. Apple still doesn't natively support sleep tracking with its wearable (although there are third-party apps you can use to track), but Fitbit has tracked sleep for years across multiple devices. The Ionic uses its continuous heart rate monitor to track pulse during sleep, which allows it to categorize your state into awake, REM, light, and deep sleep. I always enjoy looking at the sleep line graphs in the Fitbit app because I can see when I woke up and how long I was in the different sleep stages the night before. It's also clear when I don't have a good night's sleep, as my graphs show a lot more awake time than they do REM or deep sleep.

Smart TrackFitbit's Smart Track feature is also a perk that Apple Watches and Android Wear devices don't have. Smart Track automatically recognizes exercises after you've done them for a set amount of time. Smart Track has evolved over the years so you can now customize that set amount of time; I usually keep mine at 10 minutes for each activity. It's not just limited to running, biking, or other sports, either; Smart Track on my Ionic most often records periods of long walking when I'm moving around Manhattan or shopping at the mall.